This invention relates to a new and improved keyboard system and module therefor for use in an electronic voting machine. More particularly, this invention relates to a new and improved keyboard system which employs a new and improved module and a membrane having selective locations for manually depressing the membrane thereby actuating a contact switch which communicates with various circuitry for recording and tabulating a vote. A voting console to which the present application is particularly adapted is disclosed in a co-pending application Ser. No. 543,392, filed Oct. 19, 1983, which is assigned to the assignees of the present invention.
In conventional keyboard systems which employ contact switches integrated into various electronic circuitry, the contact switch generally includes a spring contact which is mounted to the circuit board. A keyboard frame receives a plurality of suitably arranged keys. Each of the keys has an upper keyface which is conventionally affixed with various indicia designating or identifying the key function, and a lowerly disposed portion which contacts against the spring contact. The spring contact is engageable with a button contact in a manner whereby manual depressing of the key against the spring contact actuates the contact switch. The spring contact has sufficient resiliency for returning the depressed key to its normal unactuated position.
In the specific application of keyboard assemblies to the design constraints presented by electronic voting machines, an important consideration is the providing of a relatively large display area for a ballot display as well as a relatively large number of keys corresponding to various candidates and/or issues to be voted. Because the specific configuration of a given ballot is likely to be different for each election and possibly for each voting precinct, it is important that the keyboard system of an electronic voting machine have means for efficiently changing the identification of the key function. In this latter regard, a membrane-type display panel can be advantageously employed to provide both a very functional keyboard system easily adaptable for incorporation into a ballot display and a very attractive aesthetically pleasing ballot display which is "friendly" to the voter. However, because of the relatively large display and keyboard area dictated by the requirements that the ballot including the offices, the instructions, and the names of the candidates be highly visible and the requirement that the keyboard system be highly reliable and responsive to the selection of a voter, unique problems are encountered in the context of an electronic voting machine in providing a keyboard system which is reliable and responsive while also benefitting from the advantages of a membrane display panel. The present invention is particularly directed to a new and improved keyboard system of a type adaptable for use in an electronic voting machine.